Flow regimes identification of air water counter current flow in vertical annulus using differential pressure signals and machine learning.

This study investigates the gas-liquid two-phase counter-current flow through a vertical annulus, a phenomenon prevalent across numerous industrial fields. The presence of an inner pipe and varying degrees of eccentricity between the inner and outer pipes often blur the clear demarcation of flow regime boundaries. To address this, we designed a vertical annulus with adjustable eccentricity (outer and inner diameters of 125 mm and 75 mm, respectively). We conducted gas-liquid counter-current flow experiments under specific conditions: gas superficial velocity ranging from 0.06 to 5.04 m/s, liquid superficial velocity from 0.01 to 0.25 m/s, and five levels of eccentricity (e = 0, 0.25, 0.5, 0.75, 1). We collected differential pressure data at two distinct height distances (DP1: 50 mm and DP2: 1000 mm). We used vectors, composed of both the probability density functions (PDFs) of the differential pressure signals and the power spectral density (PSD) reduced via Principal Component Analysis, as features. Using the CFDP clustering algorithm-based on local density-we clustered the flow regimes of the experimental data, thereby achieving an objective and consistent identification of the flow regime of gas-liquid two-phase counter-current flow in a vertical annulus. Our analysis reveals that for DP1, the main differences in the PSD of various flow regimes occur within the 0.5-1 Hz range. Among the three flow regimes involved, the slug flow exhibits the highest power intensity, followed by the bubbly flow, with the churn flow having the least. In terms of differential pressure distribution, the bubbly and churn flows have a concentrated distribution, while the slug flow is more dispersed. For DP2, the PSD differences primarily exist within the 0.5-2 Hz range. The churn flow has the highest power intensity, followed by the slug flow, with the bubbly flow being the weakest. Here, the bubbly flow's differential pressure distribution is concentrated, while the slug and churn flows are more dispersed. Based on the results of the flow regime classification, we generated a flow regime map and analyzed the influence of annulus eccentricity on the flow regime. We found that in most cases, pipe eccentricity does not significantly affect the flow regime. However, in the transition region-such as the bubbly to slug flow transition zone-flows with medium eccentricity values (e = 0.5, 0.75) are more likely to transition to slug flow. We compared the visual recognition results of flow regimes with the clustering results. 4.04% of the total samples showed different results from visual recognition and clustering, primarily located in the flow regime transition area. Since visually distinguishing flow regimes in these areas is typically challenging, our methodology offers an objective classification approach for gas-liquid two-phase counter-current flow in a vertical annulus.

Osmotic cleaning of typical inorganic and organic foulants on reverse osmosis membrane for textile printing and dyeing wastewater treatment.

Reverse osmosis (RO) is one of the most fundamental membrane technology because it has higher salt rejections, which suffers from the issue of membrane fouling, as the membrane is inevitably exposed to foulants during the filtration process. For different fouling mechanisms of RO membrane, physical and chemical cleaning are widely used in the control of RO membrane fouling. The present study investigated the performance and water flux recovery using osmotic cleaning to clean the typical inorganic and organic foulants on RO membrane for textile printing and dyeing wastewater treatment. The effects of operation conditions (i.e., the concentration of cleaning solution, the filtrating time and cleaning time, and the flow rate of cleaning solution) on relative water flux recovery were examined. The results show that a highly water flux recovery (98.3% for cleaning of inorganic fouling and 99.6% for cleaning of organic fouling) was achieved under optimal operation of the concentration and flow rate of cleaning solution and the filtrating and cleaning time. Moreover, the experiment of repeated "filtrating-cleaning" cycles indicated that the osmotic cleaning has highly performance of recoverability of water flux (over 95.0%) can be extended in a relatively long time. The experimental results and changes on SEM and AFM images of RO membrane confirmed the successful development and application of osmotic cleaning for inorganic and organic fouling of RO membrane.

Discovering the main "reinforce kidney to strengthening Yang" active components of salt Morinda officinalis based on the spectrum-effect relationship combined with chemometric methods.

Morinda officinalis, a well-known traditional herbal medicine in China, is used to treat deficiency of kidney-yang syndrome. Although this medicine has the property of "reinforcing kidney to strengthening Yang," the chemical constituents responsible for this effect remain to be elucidated. Here, we aimed to identify the main active compounds responsible for reinforcing kidney to strengthening Yang, based on spectrum-effect relationships combined with chemometrics. We used the UPLC-diode array detection method to establish the chromatography fingerprint of M. officinalis. Hydrocortisone-induced and adenine-induced kidney-yang deficiency patterns were established to evaluate the efficacy of M. officinalis. Serum triiodothyronine, free thyroxine, thyrotropin, testosterone, cortisol, luteinizing hormone, follicle-stimulating hormone, corticotropin-releasing hormone, and adrenocorticotropic hormone levels were determined as pharmacodynamic indices. Analytic hierarchy process was used to determine the weight of each index to the total pharmacodynamic contribution. Lastly, the spectrum-effect between the fingerprint and the pharmacological effects were established using grey relational analysis and partial least squares. Our findings indicated that peaks 1, 2, 3, 5, 6, 7, 8, 9, 11, 13, 15, 17, and 20 might represent the main components that positively correlated to the total effect, of which four were identified by comparison with reference standards. The identified components were monotropein (peak 1), deacetyl asperulosidic acid (peak 3), asperulosidic acid (peak 8), and asperuloside (peak 9). Our results suggest that the "reinforce kidney to strengthening Yang" effects were attributable to the combined effects of the multiple chemical components of M. officinalis and provide a valuable method to identify the active "reinforce kidney to strengthening Yang" components of M. officinalis and establish the quality control of M. officinalis.